Ludwig Wittgenstein's 'Tractatus Logico-Philosophicus' is one of the most important books of the twentieth century. It influenced philosophers and artists alike and it continues to fascinate readers today. It offers rigorous arguments but clothes them in enigmatic pronouncements. Wittgenstein himself said that his book is 'strictly philosophical and simultaneously literary, and yet there is no blathering in it'. This introduction, first published in 2005, considers both the philosophical and the literary aspects of the 'Tractatus' and shows how they are related. It also shows how the work fits into Wittgenstein's philosophical development and the tradition of analytic philosophy, arguing strongly for the vigour and significance of that tradition.